<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        *{
            margin: 0;
            padding: 0;
            height: 100%;
        }

        #left {
            float: left;
            width: 220px;
            background-color: green;
        }

        #content {
            background-color: orange;
            margin-left: 220px;/*==等于左边栏宽度==*/
        }
    </style>
</head>
<body>
<div id="left">Left sidebar</div>
<div id="content">Main Content</div>
</body>
</html>